March 2 007 Geral d Cho uinar Slide 1 doc.: IEEE 802.22-07/0112r0 Submission DTV signal stochastic behavior at the edge of the protected contour and resulting probability of detection from various sensing schemes. IEEE P802.22 Wireless RANs Date: 2007-03-11 N am e C om pany A ddress Phone em ail G erald Chouinard CRC 3701 Carling A venue, O ttaw a, O ntario, Canada K 2H 8S2 (613)998-2500 gerald.chouinard@ crc.ca Authors: Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].
Transcript
March 2007
Gerald Chouinard, CRC
Slide 1
doc.: IEEE 802.22-07/0112r0
Submission
DTV signal stochastic behavior at the edge of the protected contour and resulting probability of
Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].>
March 2007
Gerald Chouinard, CRC
Slide 2
doc.: IEEE 802.22-07/0112r0
Submission
TV signal availability at edge of contour
• Required DTV field strength: 41 dBuV/m at 615 MHz (20 log F scaling needed to compensate for the antenna effective aperture, 4π/λ2)
• Probability for DTV: F(50,90)– Location: 50% with standard deviation of 5.5 dB– Time: 90% with standard deviation depending on
distance from the transmit station
• Required DTV field strength: 64 dBuV/m
• Probability for Analog TV: F(50,50)– Location: 50% with standard deviation of 8.3 dB (VHF)
and 9.5 dB (UHF)– Time: 50% with same standard deviation as DTV
March 2007
Gerald Chouinard, CRC
Slide 3
doc.: IEEE 802.22-07/0112r0
Submission
ITU-R P.1546 propagation model• Three main propagation variations:
– Medium scale: Local ground cover variations due to obstructions in the vicinity of the receiver. Scale is in the order of these obstructions.• Propagation results were measured over 500 m to 1 km squares
– standard deviation was established with confidence over these squares– probability over adjacent squares should be statistically independent
• Flat land was assumed• Propagation results were averaged over few λ’s to
remove the impact of multipath
– Small scale: Multipath variations in the order of the wavelength typically following the Rayleigh model
– Large scale: Path variations due to changes in geometry of the entire propagation path such as presence of hills, etc.
• Need to include topographic data (TIREM, CRC-Predict, etc.)• Localization of the sensors relative to the terrain will be needed: geolocation
March 2007
Gerald Chouinard, CRC
Slide 4
doc.: IEEE 802.22-07/0112r0
Submission
ITU-R P.1546 propagation model (cont’d)
• For planning purpose:– Location variability will include a degree of multipath fading
(rooftop antenna falling in a multipath null that cannot be optimally positioned)
– It will also include some variability over greater distances.
• Probability for DTV: F(50,90)– Location: 50% with standard deviation of 5.5 dB– Time: 90% with standard deviation depending on distance
from the transmit station (variations caused by tropospheric propagation effects (e.g., ducting), leaves in deciduous trees, etc.) (σtime can be found for the given location from the predicted field strength from the difference between F(50,50) and F(50,90))
• Probability for NTSC: F(50,50)– Location: 50% with standard deviation of 8.3 dB (VHF) and
9.5 dB (UHF)– Time: 50% with same standard deviation as DTV
March 2007
Gerald Chouinard, CRC
Slide 5
doc.: IEEE 802.22-07/0112r0
Submission
Example at the edge of coverage ofa 1 MW, 300 m height DTV station
• Propagation model = ITU-R P.1546– Distance of protected contour from the DTV transmitter = 118 km– σlocation = 5.5 dB
– F(50,90) = 41 dB(μV/m) F(50,50) = 46.7 dB(μV/m)
– σtime = (F(50,50)-F(50,90))/Q-1(90%)= (56-41)/1.28= 4.46 dB
• Composite propagation– Sum of two log-normal distributions = log-normal (μ1+μ2, σ1
2+σ22)
– DTV signal variability at protected contour =
log-normal (μ= 46.7 dB(μV/m), σ= 7.08 dB)
March 2007
Gerald Chouinard, CRC
Slide 6
doc.: IEEE 802.22-07/0112r0
Submission
Example at the edge of coverage ofa 1 MW, 300 m height DTV station
• Propagation model = FCC Curves– Distance of protected contour from the DTV transmitter = 96.8 km– σlocation = 5.5 dB
– F(50,90) = 41 dB(μV/m) F(50,50) = 51.4 dB(μV/m)
– σtime = (F(50,50)-F(50,90))/Q-1(90%)= (51.4-41)/1.28= 8.12 dB
• Composite propagation– Sum of two log-normal distributions = log-normal (μ1+μ2, σ1
2+σ22)
– DTV signal variability at protected contour =
log-normal (μ= 51.4 dB(μV/m), σ= 9.8 dB)
March 2007
Gerald Chouinard, CRC
Slide 7
doc.: IEEE 802.22-07/0112r0
Submission
Channel bandwidth variability• If channel bandwidth is smaller,
there will be more flat fading occurrences due to very small excess delay (1/BW) multipath
• Sensing will be more difficult due to the additional signal fades
• Frequency fading within the useful bandwidth is treated elsewhere (captured DTV signals)
ITU-R DSB Handbook, "Terrestrial and satellite digital sound broadcasting to vehicular, portable and fixed receivers in the VHF/UHF bands", Geneva, 2002
Channel bandwidth
Rural signal standard deviation
6 MHz 5.5 dB
200 kHz 5.67 dB
80 kHz 5.9 dB
10 kHz 6.99 dB
Impact of channel bandwidth on signal variability
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
1 10 100 1000 10000
Channel bandwidth in kHz
Fa
din
g s
tan
da
rd d
ev
iati
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(d
B)
Rural
Suburban
Urban
March 2007
Gerald Chouinard, CRC
Slide 8
doc.: IEEE 802.22-07/0112r0
Submission
Conversion from field strength to SNRat input of sensing detector
• With simple OR gating of sensor reports, the Pfa will tend to increased rapidly with the number of sensors
• Pfa for individual sensors can be controlled by asking for repeated sensing times before reporting (each sensing window is independent statistically since it works against thermal noise)
• Data fusion at the base station should be based on “majority vote” (e.g., 2 out of 6 sensors) from a small number of well selected statistically independent CPEs (e.g., 6 sensors in the same topographic area located at more than 500 m) to provide a high level of probability of detection while keeping Pfa low.
